This invention relates generally to coatings and more specifically to improved extended release coating barriers comprising a film-forming polymer and a plasticizer which are applicable to drug-resin complex particles.
U.S. Pat. No. 4,221,778, the specification of which is incorporated herein by reference, describes extended release pharmaceutical compositions with which the improved coatings of this invention are applicable, namely compositions comprised of individually coated drug-resin complex particles. The examples use a coating comprised of ethylcellulose and, as a plasticizer, Durkex.RTM. 500 (partially hydrogenated cottonseed and soybean oils). It has been found, however, that the Durkex 500 has a tendency to form a cloudy precipitate when stored or shipped below about 23.degree. C.